A brief analysis of the Integer parameter transfer in Java

Java itself is a value-passing call, passing an address value to an object. Re - assign the address value is equal to re - point, does not affect the outer layer.
And there's something special about the Integer object. The implementation may be similar

class Integer{
final int value; //Once assigned, it cannot be changed.
}

This is what happens: The address value passed on the call cannot be changed and the outer + object itself cannot be changed. This value cannot be changed

There are many solutions
1. The Java style is to return a value for a single value. Return the I; Outside again I = foo (); The assignment; Multiple values using arrays or objects.
2, Pass your own wrapper class. The class MutableInteger {int value; }
3, Pass the dedicated AtomicInteger AtomicInteger object

    public static void main(String[]  parameter ) {     
  AtomicInteger i=new AtomicInteger(40);
  i.intValue();
  System.out.println(i);
 }
    public static void change(AtomicInteger i) {
     i.set(55);
}

You can also change the value after passing,
Recommend plan 1 and avoid it